Trump and Obama: The odd couple who broke ‘extended deterrence’ for the Indo-Pacific

If there is an upside to nuclear weapons it is extended deterrence. This term refers to the “nuclear umbrella” that the United States promises to extend over its closest allies in Asia and Europe to protect against hostile nuclear powers who otherwise might be tempted to act coercively against them. Although extended deterrence is most often associated with NATO, it is also a critical feature of the American hub-and-spoke alliance system in Asia. Confidence in U.S. extended deterrence guarantees is part of the glue that holds these alliances together. It is also an essential requirement for preventing nuclear proliferation by reassuring U.S. allies that they do not need their own nuclear arsenals. This key role that extended deterrence plays in underwriting nuclear nonproliferation is too often under-appreciated.

Given the vital role that extended deterrence plays in preserving the stability of the Indo-Pacific region — by bolstering U.S. alliances and warding off further nuclear proliferation and the very real associated risk of a full-blown regional nuclear arms race — it is worrisome that allied confidence in the American nuclear umbrella is fraying badly. This is the result of a one-two punch over the past decade that was delivered by the unlikely tag-team of presidents Barack Obama and Donald Trump. President Obama was a big fan of alliances, but famously not so much of nuclear weapons. Conversely, President Trump was a big fan of nuclear weapons, but famously not so much of alliances. Each acted on these impulses in ways that have seriously undercut extended deterrence. 

Despite misgivings by allies such as Japan, President Obama effectively zeroed out American nuclear warfighting capabilities in Asia by retiring the nuclear version of the sea-based Tomahawk cruise missile. The nuclear umbrella over Asia, therefore, now relies solely on intercontinental-range strategic nuclear forces that are intended primarily to deter a nuclear attack against the American homeland. President Obama also openly flirted with a no-first-use declaration, meaning the United States would unilaterally promise never to use nuclear weapons except in response to a nuclear attack against itself or its allies. 

This, in theory, would have withdrawn nuclear weapons as a deterrent against conventional attacks up to and including the full-scale invasion of an ally. Although President Obama backed off, in part due to allies’ concerns, seeds of doubt were planted about the reliability of America’s extended deterrent capabilities and commitments. These doubts have been felt more acutely in Asia than Europe because NATO has other members (Britain and France) providing nuclear deterrence, and the United States continues to deploy tactical nuclear weapons there. Indeed, Washington is now upgrading these tactical nuclear weapons as a tangible signal of its enduring extended deterrence commitments to NATO.   

The arrival of the Trump administration brought an attempt to restore nuclear credibility, putting no-first-use to rest and seeking to rebuild U.S. tactical and theater nuclear warfighting capabilities, including developing a new sea-based nuclear cruise missile. However, President Trump differently unnerved allies by harshly questioning the value of American alliances and repeatedly hinting that the United States might not be there if push ever came to shove, treaty obligations notwithstanding. The Biden administration is working to reassure shaken allies, but Trump’s alliance-bashing has planted new seeds of doubt, this time about the reliability of America’s alliance commitments writ large. In other words, allies’ confidence in extended deterrence has been battered from all sides.  

All of this is damaging because extended deterrence is powerful but also fragile. Powerful because it reassures allies that they have the protection of a nuclear superpower that could annihilate any would-be aggressor. Fragile because it requires an incredible leap of faith by friends and foes alike. To assure allies and deter potential adversaries, both need to be convinced that an American president would risk bringing nuclear devastation to the United States to prevent or avenge an attack against an ally by another major nuclear power. And not only against a nuclear attack! For example, Tokyo (and Beijing) must be convinced that there is at least a good chance that Washington would risk escalation to a civilization-ending nuclear war to honor its promise to defend some uninhabited Japanese islets in the East China Sea that are claimed by China. Really?

The stark implausibility of extended deterrence vis-à-vis conventional aggression is precisely why the mixed and inconsistent signals from presidents Obama and Trump still reverberate across allied capitals. Extended deterrence has always grappled with an inherent credibility problem, even during the Cold War when Washington avowed its unwavering bipartisan commitment. France, for example, has always scoffed at the notion that any American president would put New York at risk to save Paris, insisting that only French nuclear forces can credibly deter against coercion by a powerful nuclear-armed country such as Russia. Within strategic circles in Australia, Japan and South Korea, the question being quietly asked is whether the French may not have the right idea.  

The timing could not be worse for U.S. Indo-Pacific allies to harbor doubts about the dependability of America’s security guarantees. North Korea continues to rattle its fledgling nuclear sabre, Russia reasserts itself as a Pacific power, and military tensions simmer with an increasingly assertive China that is successfully transforming its military — conventional and nuclear — into a formidable modern force that is poised to challenge American military dominance in the region. Extended nuclear deterrence has been far less important so long as Washington and its allies have enjoyed an overwhelming military overmatch, as has been the case for three decades. But if the military balance degrades to parity or even reverses, then Washington and its allies may need to rely more and more on extended nuclear deterrence to compensate for conventional vulnerability.

President Biden stands at a crossroads as he seeks to restore the health of America’s alliances. He is moving smartly to repair the damage done by President Trump’s “America first” stance. However, he needs to think twice about reverting to President Obama’s denuclearization agenda. If the Biden administration embraces no-first-use, or begins canceling or curtailing nuclear programs, then it will give America’s allies understandable cause for doubt. There may come a time for deemphasizing extended nuclear deterrence. This is not that time.

David A. Cooper, Ph.D., is the James V. Forrestal Professor of National Security Affairs at the United States Naval War College and previously served as director of the Office of Nonproliferation Policy and director of the Office of Strategic Arms Control at the Department of Defense. He is the author most recently of “Arms Control for the Third Nuclear Age: Between Disarmament and Armageddon,” forthcoming from Georgetown University Press. All views expressed are solely his own.